Such a device is already described in U.S. Pat. No. 3 845 965. This device has the disadvantage that its band is guided only in grooves on the two sides and on the underside of the support member, not, however, on the upper side. Thus lateral borders are missing (see FIGS. 2 and 5).
The device according to Austrian Patent No. 302 129 has the disadvantage that the band, which is thicker than the height of the lateral borders and in which support axes are supported, is pressed forwardly by the ski boot over the front edge when the skier steps with the ski boot into the binding and is thus deformed.
This is also the case in the device according to Austrian Patent No. 311 231, in which the position of the band in longitudinal direction of the ski is only defined by the bend in the support member.
The band has in all known sole-support devices the shape of the jacket of a cylinder. This has the result in practice that during a twisting fall of the skier, the movement of the upper strand of the band extends laterally along a straight line and thus deviates from the circular movement of the bearing area of the sole of the ski boot. This results in a relative movement of the upper strand of the band and of the underside of the sole of the ski boot and thus an undesired additional friction, which negatively influences the release of the ski boot.
The basic purpose of the invention is to overcome this disadvantage and to provide a sole-support device in which the movement of the upper strand of the band is approximately adapted to the pivoting movement of the ski boot.
This characteristic prevents during a twisting fall of the skier a relative movement between the upper strand of the band and the underside of the sole of the ski boot, since the upper strand of the band follows approximately the same radius as the pivoting movement of the ski boot.
This effect occurs in any desired ski boot. However, if the ski boot is dimensioned according to the dimensions determined in DIN 7880, then a locating of the centerpoint of the circular arc of the groove and band to coincide with the centerpoint of the circular arc formed by the rear sole edge of the sole of the boot will be beneficial.
A construction incorporating a torsion spring for tensioning the band is slightly more complicated in its design, however, it has the advantage that the tension of the band and the pressure transmission are caused by separate elements. The elements can in this manner be dimensioned corresponding with the respective tasks.